Air conditioning apparatus



1933- s. M. ANDERSON AIR CONDITIONING APPARATUS Filed Dec. 5, 1928Patented Oct. 31, 1933 UNITED STATES PATENT OFFICE 1,933,039 AIRCONDITIONING APPARATUS Application December 5, 1928. Serial No. 323,951

3 Claims.

The present invention relates to air conditioning apparatus of thegeneral type commonly known as air washers employed for changing themoisture content and temperature condi- 5 tions of atmospheric air. atthe same time removing dust and other impurities.

In order to provide a finely divided spray of water with which contactwith the air is promoted, the common existing types of air washersemploy water nozzles having small orifices through which the water isforced under pressure. These nozzles are inefficient because the sprayis not sufficiently atomized to afford the necessary intimate contactwith the particles of the air current unless an inordinately largequantity of water is used. In fact, the amount of water vaporized by theair even under the best conditions is only a small fraction of thatsprayed through the nozzle.

Another disadvantage of the common spray nozzle is that it affords noprovision for regulation of the spray or of the amount of watervaporized by the air. In a nozzle operating under water pressure alone,the volume of the 5 spray and the degree of atomization are bothdetermined by the water pressure, and the pressure must be maintainedwithin fairly close limits to obtain any effective spray whatever. Ifthe water pressure is decreased below its optimum value, the volume ofwater passing through the nozzle is not only decreased, but the sprayeffect may be entirely lost, the water being merely forced out in acoherent stream which is useless for purposes of humidification.

The result is that the nozzle must be either on or off, no intermediatespraying conditions being permissible.

Furthermore, the orifice is well situated for the collection of dirtfrom the water, which still further reduces the efficiency of the sprayand the volume of water that can be handled. It is therefore necessaryto shut down the equipment frequently or to provide special means forperiodically cleaning the nozzles.

One object of the present invention is to provide air conditioningapparatus which is simple and inexpensive in construction, eflicient inoperation, and capable of continued use over long periods withoutnecessity for cleaning.

Another object of the invention is to provide air conditioning apparatusand method of operating the same whereby the volume of spray may benicely regulated to bring about substantially any desired degree ofhumidification with maximum efiiciency at all times.

With these and other objects in view, as will hereinafter appear, onefeature of the invention comprises a spray device of improvedconstruction by which the water is expelled into the air stream in athoroughly atomized condi tion most effective for maximum vaporization.The spray device includes a water tube to which water is continuouslysupplied, together with a compressed air nozzle for directing a blast ofcompressed air across the mouth of the water 5 tube. The water tube andcompressed air nozzle are preferably so arranged that the blast ofcompressed air produces a varying vacuum over the surface of the mouthof the water tube, that is to say, in such fashion that the surface ofthe water at the end of the tube is subjected to a vacuum gradient. Theexistence of such a. vacuum gradient is conveniently effected bydisposing the axes of the water tube and the nozzle to discharge at anangle less than 90 so that the air stream is not directly across thesurface of the tube. The presence of the vacuum gradient causes aturbulent effect in the water near the mouth of the tube, causing abreaking up of the water particles and an expulsion of them 30 into theblast of compressed air which dispels them throughout the air duct insuch a finely divided and distributed condition that they vaporizereadily in the current of atmospheric air. The apparatus is remarkablysimple and 5 efficient, it having been found that for similar degrees ofhumidiflcation, the present invention requires in some instances lessthan 10% of the water used by the common forms of spray nozzles.

Another feature of the invention consists in the means and method foraccurately regulating the quantity of the spray. According to thisfeature, water is introduced to the water tube under pressure. Thispressure may be a positive pressure or head tending to force the waterout through the tube in which case the compressed air blast is calledupon only to perform the function of creating turbulence within the tubeand dispelling atomized particles throughout the washer. Where smallerquantities of spray are required, the head may be reduced even until itbecomes negative in value and in this case, the compressed air blastperforms the additional function of applying a suction lift to thewater. In either case, the spray operates efiiciently.

Provision for adjusting the pressure or head of the water affords aconvenient regulation for the quantity of the spray. The pressure may bevaried from a large positive pressure to a large negative pressure andthe volume of spray will be correspondingly changed without loss ofefficiency and with a high degree of atomization in any case. The volumeof spray depends only upon the water pressure and the compressed airpressure, and while the regulation may be effected by a change ineither, for mechanical reasons it is preferred to maintain the airpressure constant and to regulate by variations in the head of water.

Other features of the invention consist in certain novel features ofconstruction, combinations, and arrangement of parts hereinafterdescribed and particularly defined in the claims.

In the accompanying drawing illustrating the preferred form of theinvention, Fig. 1 is a sectional elevation of the preferred form of airwasher included in a longitudinal section of the air duct, being asection on line l-1 of Fig. 2; Fig. 2 is a section on line 22 of Fig. 1transversely of the air duct; Fig. 3 is an enlarged detailed sectionalview of one of the nozzle sections shown in Fig. 1, being a section online 3-3 of Fig. 4 looking in the direction of the arrow; and Fig. 4 isa detail plan view of a part of one of the nozzle sections.

The illustrated embodiment of the invention comprises a casing 6included in or forming a part of the air duct through which theatmospheric air is blown in the direction of the arrow in Fig. 1 by anysuitable fan. The casing includes one or more sets of spray devicesindicated as two sets at 8 and 10, the former for promoting contact ofwater with the air in the lower part of the duct and the latter with theair in the upper part.

Each of the sets 8 and 10 comprises a plurality of sections which are ofthe construction shown in enlarged detail in Fig. 3. Each sectionincludes two flanges 12 at opposite ends which are connected by a waterpipe 14 and compressed air pipe 16, the flanges and the two pipes ofeach section being cast integrally. The sections are bolted togetherthrough bolt holes 18 in the flanges and as many sections may be used asare necessary to fill the width of the casing. When bolted together, thepi'pe sections 14 and 16 form respectively continuous water and airpipes extending completely across the casing.

A water tube 20 is fitted in the middle of each water pipe section by anaccurately threaded connection 22. Each compressed air pipe section 16is formed'with an air nozzle 24 having a rounded inlet 26. The mouth ofthe water tube 20 terminates in the air blast delivered by the nozzle24. It will be seen that the current of air flowing under high velocityacross the mouth of the water tube produces a vacuum which createsconditions of turbulent water flow in the tube, breaking up the waterintominute particles, and permitting them to be expelled as a fine mistinto the chamber.

It has been found that for maximum eflidisposed that a varying vacuum isproduced over ciency the water tube and nozzles should be so difierentportions of the surface of the Water tube. The preferred arrangement isshown in Fig. 3. It will be seen that the axes of the water tube and theair nozzle are disposed with relation to each other at an angle ofsomething less than so that the air current is not blown exactlyparallel to the exit surface of the tube. In its best form, the partsare so arranged that the point a which is the point of the internalsurface of the water tube extending farthest into the air stream lies inthe center line of the nozzle, and the point D which is thediametrically opposite point of the water tube lies on the extended edgeof the stream of air leaving the nozzle.

With this construction, the vacuum on the point 27 is a minimum and thaton the point a is a maximum, there being a definite gradient betweenthese two points. The result is that although the water fills the tube,it tends to rush toward the point a, thereby creating a turbulent effectat that point. This effect can actually be observed in that the waterappears to flow from the upper side of the water tube toward the lowerside where it concentrates in an eddy current whirlpool. Theconcentration of the water particles at the point a together with theirhigh velocity of turbulence, tends to throw them into the compressed airstream in a finely atomized condition; they are then picked up by thestream and carried as a radiating spray in a general direction which isopposed to the flow of fan air, as indicated in Fig. 1, in order thatintimacy of contact may be promoted by a considerable relative velocitybetween the particles of air and the spray. The effect of the nozzle isto throw a cloud of fine mist through the chamber into the atmosphericair, thereby permitting a highly intimate contact of all particles ofthe air with the atomized particles of water. Furthermore, it has beenfound that when the water tube and air nozzle have once been properlypositioned in angular relation to one another, no change in suchrelation is necessary or desirable, no matter how the head or pressureof the water may be varied. The amount of water atomized will vary withthe head or pressure of the water, but the character of the atomizationwill remain unchanged.

Compressed air is supplied to the pipe 16 by a compressor of anysuitable form connected through a valve 28 with pipes 30 and 32 leadingto the compressed air pipes of the spray devices. The compressed airsupply is entirely separate from the current of atmospheric air, andpreferably is automatically maintained at a uniform pressure.

The water supply system is described as follows: Two closed tanks 34 and36 are supported by the sides of the casing, each adapted to contain asupply of water maintained at a constant head with respect to the mouthsof the spray devices. A pipe 38 connects the water pipe sections 14 toeach set of nozzles with the water supply in the tank. The tanks 34 and36 are maintained at a suitable level by means of a supply tank 40connected by a pipe 42 with branch pipes 44 and 46, eachleading to oneof the pressure tanks and each including a regulating valve 48 and acheck valve 50. Each tank is provided with an equalizing pipe 52 whichenters the chamber 6 and is turned downwardly as shown in Fig. 2, toprevent splashing of 140 water into it. The purpose of the equalizingpipes is to place the pressure tanks under the same pressure or vacuumas the chamber 6, so that the balanced pressure existing between thetank level and the mouths of the water tubes 145 is not in any wayafiected by variations of pressure caused by changes in the velocity ofthe atmospheric air.

In operation, the water level in each of the tanks 34 and. 36 ismaintained at a defimte 150 value relative to the position of the mouthof the water tubes 20. The amount of water which each nozzle supplies inthe form of a spray is dependent upon the head of the vwater in thepressure tanks 34 and 36 and also upon the velocity of the compressedair. The head of water on the nozzles may be either positive ornegative. As shown in Fig. 2, where the water levels in the pressuretanks are below the mouths of the nozzles, the head is negative and ismeasured as a suction or lift quantitatively expressed in inches ofwater. The magnitude of this negative head is indicated at 1;. Underthese conditions, the compressed air must produce a suction suflicientto lift the water from the level of the tank to the mouth of the watertubes, as well as to create the vacuum gradient necessary for producingthe desired condition of turbulence. If the head is increased, that is,if the lift is decreased, the air pressure remaining constant, theamount of spray will be increased. The water head or pressure may beincreased to substantially any desired value up to 10 or 12 inchespositive head or even higher.

When the head is positive, the water flows by, gravity through the watertubes and is sprayed by the blast of air as fast as it approaches themouth of the tube. The same operating conditions take place, except forvariations in the density of the spray, when the head or pressure isnegative. The valves 48 controlling the flow of water to the pressuretanks will be adjusted to replenish the supply of water as it is used bythe sprays and to maintain the head at the proper value to give thedesired volume of water atomized.

If the temperature of the water is equal to the wet bulb temperature ofthe entering atmospheric air, the maximum humidiflcation will occur whenthe dry bulb temperature of the air leaving the washer is brought downto its wet bulb temperature. In this case, the relative humidity will beAny desired degree of humidification less than the theoretical maximummay be obtained by adjusting the heads in the pressure tanks. If,therefore, after operating to produce a desired humidity and temperatureof the air for a certain period, it is desired to change the airconditions, this is conveniently accomplished merely by opening orclosing the valves 48 slightly, thereby permitting the water levels inthe pressure tanks to rise or fall to different values. will beestablished under the newly adjusted pressures and the density of sprayin the chamber will be changed to suit the new conditions.

The amount of water which is taken by a single nozzle for differentheads of water and different velocities of compressed air: may be easilydetermined, and charts or tables showing the degree of humidificationand cooling of the atmospheric air at different volumes of spray mayalso be established by experiment. With an apparatus employing a givennumber of nozzles, therefore, the level necessary to be maintained inthe pressure tanks may be readily determined for substantially anydesired degree of air conditioning. A nicely regulated control of airconditions is obtainable merely by regulating the water pressure appliedto the spray water.

A similar control might be obtained by varying the velocity of thecompressed air while maintaining the water level constant, and althoughsuch control is theoretically as effective as varying the water levels,for mechanical reasons it After a short time equilibrium is preferred tooperate the air compressor under constant pressure and to regulate byvariation of head.

The casing 6 is provided at opposite sides with filters 5 which permitthe air to pass through but which'serve to catch any entrained particlesof water. The preferred filters are of metal wool which have a largenumber of small interstices to permit the air to flow without excessiveresistance but which serve effectively to catch any entrained waterparticles and permit them to run down to the bottom of the chamber. Thefilter at the inlet side of the apparatus might be omitted but for thefact that upon starting, if the water is turned on before the fan isstarted, a part of the spray might be blown into the fan. The chamber isformed at the bottom with a conical collecting basin 56 from which thedrain water is drawn 011 through a pipe 58.

The present invention commends itself not only because of itssimplicity, but also because of its economy of water and its capacityfor' accurate control. The volume of water admitted to the water tubesand atomized in the form of a spray is completely determined by the head100 of water, either positive or negative, and the velocity of thecompressed air blast. The amount of water actually vaporized, however,depends somewhat on the condition of the air and upon the degree ofhumidification which it is desired to impart'to it. In general, it isfound that if it is not desired to approach 100% humidity, practicallyall 01' the spray is vaporized, only a very small portion returning tothe drain. For approach to maximum theoretical humidification, anincreased volume of water must be employed, and since the air becomesless capable of vaporizing the spray at high humidities, a largerproportion of the water will be returned to the drain. In any case,however, the invention employs only a small proportion of the waterrequired by the usual nozzle for the same degree of conditioning.

The simplicity of the control by which the extent of humidification maybe adjusted is apparent. When the air is initially moist, or when it isnot required to humidify it completely, a small volume of spray issufficient, and at this time the water may be maintained at a negativehead, that is, at a level below the mouths of the water tubes; but forraising initially dry air to a high humidity, it may be necessary toincreasethe head to a positive value. In any case, the control iseffected merely by operation of the valves 48. Moreover, when onceadjusted, the apparatus operates continuously to maintain the proper airconditions, as distinguished from the intermittent operation of theorifice type of washer nozzle.

As a typical example of operating conditions, with a compressed airvelocity of about 10,000 feet per minute through each nozzle, the waterlevel may be varied between a positive head of 10 inches and a) negativehead of 10 inches.

It will be seen that inasmuch as the water tube 1'40 is of considerableinternal diameter (in the preferred form about of an inch) there is nopossibility of its becoming plugged by foreign matter. The spray will,therefore, operate continuously for long periods of time without thenecessity of shut-down for repairs 01' cleaning.

Any preferred apparatus for artificially raising or lowering thetemperature of the air may be employed either in front of or behind theair washer. For heating purposes, the air may be 150 caused to contactwith heated surfaces such as steam coils, and for cooling purposes,either the air may be passed over cool surfaces or the spray water maybe refrigerated to a low temperature.

It will be understood that when the water is approximately at the wetbulb temperature of the entering air, the maximum theoretical cooling ofthe air without additional means will occur when its humidity is raisedto 100%, the dry bulb and wet bulb temperatures then being equal. If thewater is artificially cooled below the wet bulb temperature of the air,the air will first be cooled to its wet bulb temperature by conversionof sensible heat into latent heat of vaporization of the water,assuming, of course, that a. sufficient volume of spray is employed toeflect substantially 100%humidification. Cooling below the wet bulbtemperature is then brought about by. mechanical transfer of heatbetween the air and the artificially cooled water particles.

The invention having been thus described, what is claimed is:

1. Air conditioning apparatus comprising a chamber through which the airbeing conditioned flows, a liquid tube, a compressed air nozzle forblowing a blast of air across the mouth of the tube, means for supplyingliquid to the tube including a tank connected with the tube, means formaintaining a constant level of liquid in the tank, and means forregulating the liquid level to produce a positive or negative head withrespect to the mouth of the tube to control the volume of the spray.

2. Air conditioning apparatus comprising a chamber through which the airto be conditioned flows, a liquid tube, a compressed air nozzle forblowing a blast of air across the mouth of the tube, means for supplyingliquid to the tube including a tank connected with the tube, means formaintaining a constant level of liquid in the tank, and means forregulating the liquid level to vary the head with respect to the mouthof the tube to control the volume of the spray, and means forestablishing an equalizing connection between the tank above the levelof the liquid and the chamber whereby the head is uninfluenced bypressure changes due to the velocity of the air to be conditioned.

3. A spray device for air conditioning apparatus comprising a sectionhaving bolting flanges at opposite ends and a water pipe and acompressed air pipe, the compressed air pipe having a nozzle, and awater tube communicating with the water pipe and terminating in the pathof air flow directed by the nozzle.

SAMUEL M. ANDERSON.

